The present invention relates generally to an adaptive safety restraint system. In particular, the present invention is directed to a safety restraint system employing an electrically actuated throttling or control valve device for adaptively controlling the output of an inflator during air bag inflation.
Safety restraint systems are used in motor vehicles for protecting the vehicle occupants during collisions. In addition to seat belts, many safety restraint systems now include a driver-side air bag mounted in the steering wheel and a passenger-side air bag mounted in the dashboard. Furthermore, recent attention has been directed to incorporation of other restraint devices such as, for example, side air bags, seat belt pretensioners, and energy management retractors into the safety restraint system. Many, if not all, of these restraint devices are activated by the vehicle's crash management system in response to detection of a vehicular collision exceeding a predetermined impact magnitude.
Many air bag and safety restraint devices such as a pretensioner (also called a belt tightener) are deployed in response to activation of an inflator or other pyrotechnic, gas generating device by the vehicle's crash management system. Typically, activation of the inflator (pyrotechnic device) generates a predetermined output, based on the magnitude of gas or propellant discharge, for deploying its associated air bag or safety restraint device. However, in order to optimize occupant protection during a collision, it is desirable to vary the deployment characteristics of the air bags and/or the operational characteristics of the other restraint devices based on various control parameters such as, for example, the severity of the crash, belt usage, and the position, size and weight of the seat occupant. Thus, the vehicle's crash management system includes various sensors for detecting and/or measuring such control parameters and a controller for adaptively varying the inflator output in response to the sensor signals.
One method for regulating the output of an inflator is through the use of an inflator having two or more separate stored energy devices, commonly referred to as a multi-level inflator. Typically, such multi-level inflators include a first stored energy device, that is, a quantity of propellant which burns to produce the inflation gas and an initiator (squib or detonator) to cause the propellant to burn and a second stored energy device having a different amount of propellant, each of which can be independently activated. In response to a relatively minor crash, only the first stored energy device is activated. Likewise, in a more severe crash, only the second stored energy device is activated. However, in a high severity crash, both stored energy devices are simultaneously activated for providing maximum inflator output. Multi-level inflators can alternatively be used for regulating inflator output in response to the size of the vehicle occupant, if used in conjunction with the appropriate occupant detection sensors. However, multi-level inflators are expensive to manufacture because of the need to integrate two separate stored energy devices into a single inflator unit. Moreover, even if only one of the stored energy devices is discharged, the entire inflator must still be replaced.
Accordingly, it is desirable to provide a lower cost system for controlling the mass flow and pressure of gas generated by the inflator. One such approach is to provide a single inflator having one or more control valve devices for selectively modulating the inflator output and adaptively controlling the deployment force provided to the safety restraint device.
Accordingly, the present invention is directed to an adaptively controlled safety restraint system. The safety restraint system includes a safety restraint device operative in response to a flow of pressurized gas, and an inflator having a stored energy device which can be activated to produce pressurized gas which is discharged through an exhaust port for driving a single safety restraint device or a plurality of such devices communicated to the inflator with a manifold and conduit. The safety restraint system further includes a valve assembly disposed between the inflator and the safety restraint device for controllably varying or throttling the output of the inflator. The valve assembly is controlled by an actuator(s) in response to an electrical signal received from a crash management controller.